Technical Field
This disclosure relates to image processing, and more specifically to performing separate range tone mapping on combined images.
Description of the Related Art
Tone mapping can be important when capturing, storing and reproducing images because often the bit depth of the image's pixels have a limited dynamic range that is inadequate to capture all of the light intensities present in real-life scenes. Accordingly, tone maps specify which ranges of luminance are mapped to each bit value. General tone maps can be applied to images regardless of the content of the images. For example, tone map bit values may be allocated evenly across the luminance spectrum. However, tone maps can also be adapted based on image content to best represent the real-life scene captured in the image. For example, a scene that is dark or mostly shadowed may use a tone map that allocates more bit values to the darker end of the luminance spectrum than a tone map for an average scene. Similarly, a scene that is particularly bright or light may use a tone map that allocates more bits values to the lighter end of the luminance spectrum than a tone map for an average scene. However, when a scene contains both shadowed and bright features, application of a single tone map may compress features on either edge of the spectrum due to the limited bit depth of the tone map.